MalStone: Towards A Benchmark for Analytics on Large Data Clouds

Developing data mining algorithms that are suitable for cloud computing platforms is currently an active area of research, as is developing cloud computing platforms appropriate for data mining. Currently, the most common benchmark for cloud computing is the Terasort (and related) benchmarks. Although the Terasort Benchmark is quite useful, it was not designed for data mining per se. In this paper, we introduce a benchmark called MalStone that is specifically designed to measure the performance of cloud computing middleware that supports the type of data intensive computing common when building data mining models. We also introduce MalGen, which is a utility for generating data on clouds that can be used with MalStone

Piecewise smooth systems near a co-dimension 2 discontinuity manifold: can one say what should happen?

We consider a piecewise smooth system in the neighborhood of a co-dimension 2 discontinuity manifold $\Sigma$. Within the class of Filippov solutions, if $\Sigma$ is attractive, one should expect solution trajectories to slide on $\Sigma$. It is well known, however, that the classical Filippov convexification methodology is ambiguous on $\Sigma$. The situation is further complicated by the possibility that, regardless of how sliding on $\Sigma$ is taking place, during sliding motion a trajectory encounters so-called generic first order exit points, where $\Sigma$ ceases to be attractive. In this work, we attempt to understand what behavior one should expect of a solution trajectory near $\Sigma$ when $\Sigma$ is attractive, what to expect when $\Sigma$ ceases to be attractive (at least, at generic exit points), and finally we also contrast and compare the behavior of some regularizations proposed in the literature. Through analysis and experiments we will confirm some known facts, and provide some important insight: (i) when $\Sigma$ is attractive, a solution trajectory indeed does remain near $\Sigma$, viz. sliding on $\Sigma$ is an appropriate idealization (of course, in general, one cannot predict which sliding vector field should be selected); (ii) when $\Sigma$ loses attractivity (at first order exit conditions), a typical solution trajectory leaves a neighborhood of $\Sigma$; (iii) there is no obvious way to regularize the system so that the regularized trajectory will remain near $\Sigma$ as long as $\Sigma$ is attractive, and so that it will be leaving (a neighborhood of) $\Sigma$ when $\Sigma$ looses attractivity. We reach the above conclusions by considering exclusively the given piecewise smooth system, without superimposing any assumption on what kind of dynamics near $\Sigma$ (or sliding motion on $\Sigma$) should have been taking place.Comment: 19 figure

k-core organization of complex networks

We analytically describe the architecture of randomly damaged uncorrelated networks as a set of successively enclosed substructures -- k-cores. The k-core is the largest subgraph where vertices have at least k interconnections. We find the structure of k-cores, their sizes, and their birth points -- the bootstrap percolation thresholds. We show that in networks with a finite mean number z_2 of the second-nearest neighbors, the emergence of a k-core is a hybrid phase transition. In contrast, if z_2 diverges, the networks contain an infinite sequence of k-cores which are ultra-robust against random damage.Comment: 5 pages, 3 figure

ФОРМИРОВАНИЕ ТРЕХМЕРНЫХ СТРУКТУР В ПОДЛОЖКАХ КАРБИДА КРЕМНИЯ ПЛАЗМОХИМИЧЕСКИМ ТРАВЛЕНИЕМ

This article is a review of the technology for the formation of three−dimensional structures in silicon carbide substrates. The technological solution of these problems ion−stimulation plasmochemistry etching in its various modifications, the most successful being by ICP sources (sources of inductively coupled plasma).Silicon carbide consists of silicon and carbon which produce volatile fluorides in reaction with fluorine. Therefore for plasmochemistry etching of silicon carbide one uses fluorine−containing gases, most often sulfur hexafluoride (SF6), and sometimes with additions of oxygen and argon. During plasmochemistry etching of silicon carbide one  uses the  mask  the  material  of which does not interact with fluorine.  As a rule these are thin films of metals, e.g.  Cu, Al and Ni, and sometimes films of silicon oxides.The most  important technological trend of this process is making through holes  by etching of SiC substrates with GaN epitaxial layers, and their subsequent metallization.In this review we will present examples of ICP source applications for the formation of micro− and nano−sized three−dimensional structures in silicon carbide substrates, including  making  through holes  in SiC substrates with GaN epitaxial layers.Представлен обзор, посвященный технологии формирования трехмерных структур в подложках  карбида кремния. Технологически эта задача решается ионно−стимулированным плазмо-химическим травлением в различных его вариациях, и наиболее успешно — с помощью источника с индуктивно связанной плазмой (ICP).Карбид  кремния состоит из кремния и углерода, которые в реакции со фтором образуют летучие фториды. Реакция травления идет при взаимодействии кремния и углерода с активными радикалами и ионами фтора. Поэтому для плазмохимического травления карбида кремния используют фторсодержащий газ, в большинстве случаев — шестифтористую серу SF6 (часто с добавкой кислорода и иногда  аргона). В качестве масок при плазмохимическом травлении карбида кремния применяют  материалы, не взаимодействующие с фтором. Преимущественно это пленки металлов Cu, Al и Ni, реже — пленки оксида кремния.Особо  важное технологическое направление, связанное с плазмохимическим травлением подложек SiC с нанесенными на них эпитаксиальными слоями GaN, — это получение в них сквозных  отверстий и их последующая металлизация.Приведены примеры использования источников ICP для формирования трехмерных структур с микро− и наноразмерами в карбиде кремния.В том числе рассмотрено формирование сквозных  отверстий в подложках карбида кремния с эпитаксиальными слоями нитрида галлия

Turning points: the personal and professional circumstances that lead academics to become middle managers

In the current higher education climate, there is a growing perception that the pressures associated with being an academic middle manager outweigh the perceived rewards of the position. This article investigates the personal and professional circumstances that lead academics to become middle managers by drawing on data from life history interviews undertaken with 17 male and female department heads from a range of disciplines, in a post-1992 UK university. The data suggests that experiencing conflict between personal and professional identities, manifested through different socialization experiences over time, can lead to a ‘turning point’ and a decision that affects a person’s career trajectory. Although the results of this study cannot be generalized, the findings may help other individuals and institutions move towards a firmer understanding of the academic who becomes head of department—in relation to theory, practice and research